2004 YAMAHA YZ85 engine

2 - 16
SPEC
EC240000
CABLE ROUTING DIAGRAM
1Hose guide
2Brake hose
3Throttle cable
4Fuel tank breather hose
5Engine stop switch lead
6CDI magneto lead
7Clamp
8Carburetor breather hose
9Carburetor overflow hose
0Transmission oil breather hose
ARadiator breather hose
BClutch cable
CSpark plug leadDCable guide
EBrake hose holder
ÈPass the fuel tank breather hose between the
handlebar and tension bar, then insert its end
into the hole of the steering stem.
ÉFasten the ground lead together with the ignition
coil.
ÊClamp the brake hose with the brake hose
holder.
ËFit the brake hose into the guides of the protec-
tor.
CABLE ROUTING DIAGRAM

2 - 18
SPEC
1Throttle cable
2Clutch cable
3Clamp
4Engine stop switch lead
5Brake hose
6Hose guideÈFasten the engine stop switch lead to the han-
dlebar with the plastic band.
ÉPass the brake hose in front of the number plate.
ÊCross the clutch cable and throttle cable over
the number plate boss.
CABLE ROUTING DIAGRAM

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh mixture of oil and gasoline is filled in the fuel
tank. Check the fuel line for leakage.P.1-12
Transmission oilCheck that the oil level is correct. Check the crankcase for leak-
age.P.3-12 ~ 13
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10
Brakes Check the play of front brake and effect of front and rear brake. P.3-16 ~ 21
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-22 ~ 24
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-31 ~ 32
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-32 ~ 34
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-24 ~ 30
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Exhaust pipe and silencerCheck that the exhaust pipe is tightly mounted and has no
cracks.P.4-2
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-22
Lubrication Check for smooth operation. Lubricate if necessary. P.3-35
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-16
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 19

3 - 5
INSP
ADJ
EC350000
ENGINE
COOLANT LEVEL INSPECTION
WARNING
Do not remove the radiator cap
1, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
CAUTION:
Hard water or salt water is harmful to the
engine parts. You may use distilled water, if
you can’t get soft water.
5PA30010
1. Place the machine on a level place, and
hold it in an upright position.
2. Remove:

Radiator cap
3. Check:

Coolant level
Coolant level a low → Add coolant.
1Radiator
5PA30020
ENGINE/COOLANT LEVEL INSPECTION

3 - 6
INSP
ADJ
COOLANT REPLACEMENT
COOLANT REPLACEMENT
WARNING
Do not remove the radiator cap when the
engine is hot.
CAUTION:
Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:

Coolant drain bolt 1
3. Remove:

Radiator cap
Drain the coolant completely.
4. Clean:

Cooling system
Thoroughly flush the cooling system with
clean tap water.
5. Install:

Copper washer

Coolant drain bolt
5PA30030
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
6. Fill:

Radiator

Engine
To specified level.
Recommended coolant:
High quality ethylene glycol
anti-freeze containing anti-
corrosion for aluminum engine
Coolant
1 and water (soft water)
2
mixing ratio:
50 %/50 %
Coolant capacity:
0.54 L (0.48 Imp qt, 0.57 US qt)
5PA30040

3 - 7
INSP
ADJ
RADIATOR CAP INSPECTION
CAUTION:

Do not mix more than one type of ethyl-
ene glycol antifreeze containing corro-
sion inhibitors for aluminum engine.

Do not use water containing impurities or
oil.
7. Install:

Radiator cap
Start the engine and warm it up for a sev-
eral minutes.
8. Check:

Coolant level
Coolant level low → Add coolant. Handling notes of coolant:
The coolant is harmful so it should be han-
dled with special care.
WARNING

When coolant splashes to your eye.
Thoroughly wash your eye with water
and see your doctor.

When coolant splashes to your clothes.
Quickly wash it away with water and
then with soap.

When coolant is swallowed.
Quickly make him vomit and take him
to a doctor.
EC355000
RADIATOR CAP INSPECTION
1. Inspect:

Seal (radiator cap) 1

Valve and valve seat 2
Crack/damage → Replace.
Exist fur deposits 3 → Clean or replace.
5PA30050

3 - 10
INSP
ADJTHROTTLE CABLE ADJUSTMENT/
THROTTLE LUBRICATION
EC35A001
THROTTLE CABLE ADJUSTMENT
1. Check:

Throttle grip free play a
Out of specification → Adjust.
Throttle grip free play
a:
3 ~ 5 mm (0.12 ~ 0.20 in)
5PA30110
2. Adjust:

Throttle grip free play
Throttle grip free play adjustment steps:

Loosen the locknut 1.

Turn the adjuster 2 until the specified free
play is obtained.

Tighten the locknut.
NOTE:
Before adjusting the throttle cable free play,
the engine idle speed should be adjusted.
WARNING
After adjusting, turn the handlebar to
right and left and make sure that the
engine idling does not run faster.
5PA30120
THROTTLE LUBRICATION
1. Remove:

Throttle cable cap 1
5PA30130
2. Apply:

Lithium soap base grease
On the throttle cable end a and tube guide
cable winding portion b.
3. Install:

Throttle grip cap
5PA30140
T R..1 Nm (0.1 m · kg, 0.7 ft · lb)

3 - 11
INSP
ADJ
AIR FILTER CLEANING
AIR FILTER CLEANING
NOTE:
Proper air filter maintenance is the biggest key
to preventing premature engine wear and
damage.
CAUTION:
Never run the engine without the air filter
element in place; this would allow dirt and
dust to enter the engine and cause rapid
wear and possible engine damage.
1. Remove:

Seat

Fitting bolt 1

Washer 2

Air filter element 3

Air filter guide 4
5PA30150
2. Clean:

Air filter element
Clean them with solvent.
NOTE:
After cleaning, remove the remaining solvent
by squeezing the element.
CAUTION:

Do not twist the element when squeezing
the element.

Leaving too much of solvent in the ele-
ment may result in poor starting.
5PA30160
3. Inspect:

Air filter element
Damage → Replace.
4. Apply:

Foam-air-filter oil or equivalent oil
To the element.
NOTE:
Squeeze out the excess oil. Element should be
wet but not dripping.